Method and apparatus for determining a direct measure of quality in a packet-switched network

ABSTRACT

A method and system for analyzing deficiencies in a packet-switched network is described. In one example, network measurement data pertaining to components within a packet-switched network are obtained. Reliability estimates of access networks and associated access links coupled to the packet-switch network are conducted. Lastly, an end-to-end direct measure of quality (DMOQ) is calculated from the network measurement data and network estimation data derived from the reliability estimates.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to communicationnetworks and, more particularly, to a method and apparatus fordetermining a direct measure of quality in a packet-switched network,e.g., a Voice over Internet Protocol (VoIP) network.

2. Description of the Related Art

Generally, telecommunications systems provide the ability for two ormore people or machines (e.g., computerized or other electronic devices)to communicate with each other. A telecommunications system may includevarious networks for facilitating communication that may be generallyorganized into packet-switched networks and circuit-switched networks.Exemplary packet-switched networks include internet protocol (IP)networks, asynchronous transfer mode (ATM) networks, frame-relaynetworks, and the like. An exemplary circuit-switched network includes aplain old telephone system (POTS), such as the publicly switchedtelephone network (PSTN). Although circuit-switched networks havetraditionally been used to provide an effective means for voicecommunication, packet-switched networks are currently being utilized ona more frequent basis. Another example of packet-switched networks is aVoice over Internet Telephony (VoIP) network.

Providers of these types of networks may set “direct measures ofquality” (DMOQs) to gauge the reliability and quality of the servicestheir networks offer. For example, a network provider may establishDMOQs capable of measuring call setup rates and the service availabilityof a network. These DMOQs are typically influenced by a number offactors. Network component defects, human error, access deficiencies,and transport disruptions are examples of considerations that contributetoward the reduction of a DMOQ. Although most factors that contribute toDMOQs can be directly measured and controlled, other determinants, suchas components associated with access networks, are beyond the directvisibility of a particular network provider and make the determinationof a DMOQ problematic.

Accordingly, there exists a need in the art for a method and apparatusfor determining an end-to-end DMOQ in a reliable and efficient manner.

SUMMARY OF THE INVENTION

In one embodiment, a method and system for analyzing deficiencies in apacket-switched network is described. More specifically, networkmeasurement data pertaining to components within a packet-switchednetwork are obtained. Reliability estimates of access networks andassociated access links coupled to the packet-switch network areconducted. Lastly, an end-to-end direct measure of quality (DMOQ) iscalculated from the network measurement data and network estimation dataderived from the reliability estimates.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 illustrates an exemplary Voice over Internet Protocol (VoIP)network related to the present invention;

FIG. 2 is a flow diagram depicting an exemplary embodiment of a methodfor determining an end-to-end direct measure of quality in apacket-switched network in accordance with the invention; and

FIG. 3 is a block diagram depicting an exemplary embodiment of acomputer suitable for implementing the processes and methods describedherein.

DETAILED DESCRIPTION

To better understand the present invention, FIG. 1 illustrates anexample network, e.g., a packet-switched network such as a VoIP networkrelated to the present invention. The VoIP network may comprise varioustypes of customer endpoint devices connected via various types of accessnetworks to a carrier (a service provider) VoIP core infrastructure overan Internet Protocol/Multi-Protocol Label Switching (IP/MPLS) based corebackbone network. Broadly defined, a VoIP network is a network that iscapable of carrying voice signals as packetized data over an IP network.An IP network is broadly defined as a network that uses InternetProtocol to exchange data packets.

The customer endpoint devices can be either Time Division Multiplexing(TDM) based or IP based. TDM based customer endpoint devices 122, 123,114, and 135 typically comprise of TDM phones or Private Branch Exchange(PBX). IP based customer endpoint devices 144 and 145 typically compriseIP phones or PBX. The Terminal Adaptors (TA) 132 and 133 are used toprovide necessary interworking functions between TDM customer endpointdevices, such as analog phones, and packet based access networktechnologies, such as Digital Subscriber Loop (DSL) or Cable broadbandaccess networks. TDM based customer endpoint devices access VoIPservices by using either a Public Switched Telephone Network (PSTN) 120,121 or a broadband access network via a TA 132 or 133. IP based customerendpoint devices access VoIP services by using a Local Area Network(LAN) 140 and 141 with a VoIP gateway or router 142 and 143,respectively.

The access networks can be either TDM or packet based. A TDM PSTN 120 or121 is used to support TDM customer endpoint devices connected viatraditional phone lines. A packet based access network, such as FrameRelay, ATM, Ethernet or IP, is used to support IP based customerendpoint devices via a customer LAN, e.g., 140 with a VoIP gateway androuter 142. A packet based access network 130 or 131, such as DSL orCable, when used together with a TA 132 or 133, is used to support TDMbased customer endpoint devices.

The core VoIP infrastructure comprises of several key VoIP components,such the Border Element (BE) 112 and 113, the Call Control Element (CCE)111, and VoIP related servers 114. The BE resides at the edge of theVoIP core infrastructure and interfaces with customers endpoints overvarious types of access networks. A BE is typically implemented as aMedia Gateway and performs signaling, media control, security, and calladmission control and related functions. The CCE resides within the VoIPinfrastructure and is connected to the BEs using the Session InitiationProtocol (SIP) over the underlying IP/MPLS based core backbone network110. The CCE is typically implemented as a Media Gateway Controller andperforms network wide call control related functions as well asinteracts with the appropriate VoIP service related servers whennecessary. The CCE functions as a SIP back-to-back user agent and is asignaling endpoint for all call legs between all BEs and the CCE. TheCCE may need to interact with various VoIP related servers in order tocomplete a call that require certain service specific features, e.g.translation of an E.164 voice network address into an IP address.

For calls that originate or terminate in a different carrier, they canbe handled through the PSTN 120 and 121 or the Partner IP Carrier 160interconnections. For originating or terminating TDM calls, they can behandled via existing PSTN interconnections to the other carrier. Fororiginating or terminating VoIP calls, they can be handled via thePartner IP carrier interface 160 to the other carrier.

In order to illustrate how the different components operate to support aVoIP call, the following call scenario is used to illustrate how a VoIPcall is setup between two customer endpoints. A customer using IP device144 at location A places a call to another customer at location Z usingTDM device 135. During the call setup, a setup signaling message is sentfrom IP device 144, through the LAN 140, the VoIP Gateway/Router 142,and the associated packet based access network, to BE 111. BE 111 willthen send a setup signaling message, such as a SIP-INVITE message if SIPis used, to CCE 111. CCE 111 looks at the called party information andqueries the necessary VoIP service related server 114 to obtain theinformation to complete this call. If BE 113 needs to be involved incompleting the call; CCE 111 sends another call setup message, such as aSIP-INVITE message if SIP is used, to BE 113. Upon receiving the callsetup message, BE 113 forwards the call setup message, via broadbandnetwork 131, to TA 133. TA 133 then identifies the appropriate TDMdevice 135 and rings that device. Once the call is accepted at locationZ by the called party, a call acknowledgement signaling message, such asa SIP-ACK message if SIP is used, is sent in the reverse direction backto the CCE 111. After the CCE 111 receives the call acknowledgementmessage, it will then send a call acknowledgement signaling message,such as a SIP-ACK message if SIP is used, toward the calling party. Inaddition, the CCE 111 also provides the necessary information of thecall to both BE 111 and BE 113 so that the call data exchange canproceed directly between BE 111 and BE 113. The call signaling path 150and the call data path 151 are illustratively shown in FIG. 1. Note thatthe call signaling path and the call data path are different becauseonce a call has been setup up between two endpoints, the CCE 111 doesnot need to be in the data path for actual direct data exchange.

Note that a customer in location A using any endpoint device type withits associated access network type can communicate with another customerin location Z using any endpoint device type with its associated networktype as well. For instance, a customer at location A using IP customerendpoint device 144 with packet based access network 140 can callanother customer at location Z using TDM endpoint device 123 with PSTNaccess network 121. The BEs 111 and 113 are responsible for thenecessary signaling protocol translation, e.g., SS7 to and from SIP, andmedia format conversion, such as TDM voice format to and from IP basedpacket voice format.

The VoIP related server 114, which is coupled to the packet-switchednetwork 110, may be any type of computer or device that stores data,manages network resources, and performs other conventional computingfunctions. Depending on the particular embodiment, there may be one ormore VoIP related servers coupled to the network 110. The server 114 mayalso contain a database 138. The database may be an electronic filingsystem or any collection of information organized in such a way that theserver 114 can quickly select desired pieces of data. In one embodiment,the database 138 may store network measurement data 140 obtained by theDMOQ module 144, which also resides on the server 114. The networkmeasurement data 140 constitutes a portion of the requisite informationneeded to ultimately create a DMOQ. The network measurement data 140 maycomprise information relating to various performance aspects of thenetwork components (e.g., border elements 112) that may be derived orobtained directly from the network 110. In one embodiment, the networkmeasurement data 140 may comprise fit rates, failover characteristics,redundancy, and power source reliability indexes (e.g., mean time tofailure (MTTF)) of the network components.

More specifically, the fit rate of a network component may represent thedegree of reliability that the component will be compatible with thenetwork 110. The failover characteristics describe the ability of anetwork component to cooperate and provide a backup functionality. Forexample, a plurality of network components may communicate with oneanother to facilitate failovers such that when software or hardwarebecome inoperative on a particular network component, another componentcan quickly execute the same function as the inoperative componentwithout significant interruption. As such, a user of services that aresupported by the inoperative component would not be substantiallyimpacted by an inoperative server or software. Whereas the failovercharacteristics describe a component's effectiveness to back up anothercomponent in the network, redundancy may relate to the actual number ofbackup components. More specifically, the greater the number ofredundant components existing in a network directly correlates to thenumber of possible paths a network can use to handle or route a givencall flow.

In addition to component properties and characteristics, the networkmeasurement data may also include other information obtained directlyfrom the network. In one embodiment, this data may come from call flowtracing information obtained by a VoIP related server (e.g., a signalingtracer server (STS)), Call Detail Records (CDRs), and the like. A CDR isdata associated with a telephone call, including the calling and thecalled numbers, the date and timestamp, the duration, the call setupdelay, the final handling code, along with other performance relateddata, such as packet loss and delay of the telephone call. The finalhandling code is the code that indicates whether a call has beencompleted successfully, blocked or cut off.

Likewise, the database 138 may store the requisite network estimationdata 142 ultimately needed to determine a DMOQ. In one embodiment, thenetwork estimation data 142 comprises performance data pertaining toaccess network and associated network access links that may be involvedin particular service provided by the network provider. For example, ifa DMOQ was desired for call flow reliability, the component reliabilitycharacteristics of the access networks and access network elementsthrough which the “end-to-end” call signaling flow and call mediatravels during a particular call flow would be required. However, thecomplete end-to-end signaling path (as well as the entire media path)may include other components that are positioned outside the core VoIPnetwork 110. For instance, the call flow may have to traverse anothercable provider's broadband network via connecting access links (see FIG.1). Since a end-to-end DMOQ is dependent on core VoIP networkcomponents, access networks, and various access links, the “unknown”contribution made by the access networks and access must ultimately beestimated.

To obtain this type of information, data collecting “probes” may have tobe deployed by the network provider in order to gauge the overallservice quality and reliability of any relevant access network (e.g.,DSL/cable network 131). These probes may include time stamped requestsin order to measure an access network's tendency to exhibit jitter ortest scripts used to measure an access network's reliability (i.e.,transmitting an “x” number of test script packets and determining if “x”packets return) and call capacity. Likewise, the access links associatedwith an access network would be included in the network estimation data.

For example, the access links which connect the core VoIP network 110 tothe calling and receiving endpoint devices (and intervening accessnetworks), should be assessed. Notably, the estimated performancecharacteristics of the access links connecting the VoIP network 110 withthe access network would constitute a portion of the network estimationdata. Characteristics of the access links, such as signal degenerationqualities, bandwidth capacity, susceptibility to interference, and thelike are useful in determining estimates of the contributions made bythe network access links associated with the access networks toward theoverall reliability of a particular service provided by the networkprovider. In one embodiment, this access link information is similarlyobtained by network probes deployed by the network provider and providedto the server 114.

FIG. 2 is a flow diagram depicting an exemplary embodiment of a method200 method for determining a direct measure of quality (DMOQ) for aprovided service in a packet-switched network in accordance with theinvention. Aspects of the method 200 may be understood with reference tothe VoIP network of FIG. 1.

The method 200 begins at step 202. At step 204, network measurement data140 is obtained. In one embodiment, this data may be directly obtainedfrom a server 114. Specifically, the server 114 obtains this datadirectly from the network components that may be utilized to provide theparticular service. This data is acquired over a predetermined period oftime. For example, the data may include recently obtained data oralternatively, data that has been acquired over a long time period, andis subsequently stored in a database 138 for later use. In the event aDMOQ must be calculated, the DMOQ module 144 obtains the requisitenetwork measurement data from the database. In another embodiment, theserver 114 obtains the network measurement data directly from thenetwork 110 for immediate processing. As discussed above, the networkmeasurement data may include component fit rates, component failovercharacteristics, CDRs, call flow tracing information, and the like.Essentially, the network measurement data 140 may comprise any type ofdata that can be directly obtained from the core VoIP network 110 andcan be used to determine the DMOQ of a service offered by a networkprovider.

The method 200 then continues to step 206, where network estimate data142 is acquired. In one embodiment, the network estimate data 142 isobtained by deploying probes capable of estimating various aspects ofaccess network components and access networks that can be used to assessthe reliability and quality of service of a particular access networkand associated access links. The probes may accomplish this by acquiringmeasurements of data packet loss, jitter exhibited, and the like.Essentially, the network measurement data 140 may comprise any type ofdata pertaining to the access networks or associated network accesslinks that contribute to the overall reliability and/or quality of aparticular service offered by a network provider and cannot be directlyobtained from the core VoIP network 110.

At step 208, a DMOQ for the particular network service is derived fromthe network measurement data and the network estimation data. In oneembodiment, the DMOQ module 144 processes the network measurement dataand network estimation data obtained and stored by the server 114. Morespecifically, the DMOQ module 144 computes the exact contribution of theknown VoIP network components using the network measurement datarelevant to the network service in question (e.g., a component'scontribution toward call flow service reliability if a DMOQ for callflow reliability is required). Similarly, the DMOQ module 144 conductsreliability estimates for each of the access networks and associatedaccess links that are utilized to provide the particular networkservice. After performing these computations, the DMOQ produces a DMOQthat measures the reliability (and/or quality) of the particularservice. The method 200 proceeds to step 210 and ends.

FIG. 3 is a block diagram depicting an exemplary embodiment of acomputer 300 suitable for implementing the processes and methodsdescribed herein. For example, the computer 300 may be used to implementthe call control element 111, border elements 112, 113, and the like ofFIG. 1. The computer 300 includes a central processing unit (CPU) 301, amemory 303, various support circuits 304, and an I/O interface 302. TheCPU 301 may be any type of microprocessor known in the art. The supportcircuits 304 for the CPU 301 include conventional cache, power supplies,clock circuits, data registers, I/O interfaces, and the like. The I/Ointerface 302 may be directly coupled to the memory 303 or coupledthrough the CPU 301. The I/O interface 302 may be coupled to variousinput devices 312 and output devices 311, such as a conventionalkeyboard, mouse, printer, display, and the like.

The memory 303 may store all or portions of one or more programs and/ordata to implement the processes and methods described herein. Althoughone or more aspects of the invention are disclosed as being implementedas a computer executing a software program, those skilled in the artwill appreciate that the invention may be implemented in hardware,software, or a combination of hardware and software. Suchimplementations may include a number of processors independentlyexecuting various programs and dedicated hardware, such as ASICs.

The computer 300 may be programmed with an operating system, which maybe OS/2, Java Virtual Machine, Linux, Solaris, Unix, Windows, Windows95,Windows98, Windows NT, and Windows2000, WindowsME, and WindowsXP, amongother known platforms. At least a portion of an operating system may bedisposed in the memory 303. The memory 303 may include one or more ofthe following random access memory, read only memory, magneto-resistiveread/write memory, optical read/write memory, cache memory, magneticread/write memory, and the like, as well as signal-bearing media asdescribed below.

An aspect of the invention is implemented as a program product for usewith a computer system. Program(s) of the program product definesfunctions of embodiments and can be contained on a variety ofsignal-bearing media (e.g., computer readable media), which include, butare not limited to: (i) information permanently stored on non-writablestorage media (e.g., read-only memory devices within a computer such asCD-ROM or DVD-ROM disks readable by a CD-ROM drive or a DVD drive); (ii)alterable information stored on writable storage media (e.g., floppydisks within a diskette drive or hard-disk drive or read/writable CD orread/writable DVD); or (iii) information conveyed to a computer by acommunications medium, such as through a computer or telephone network,including wireless communications. The latter embodiment specificallyincludes information downloaded from the Internet and other networks.Such signal-bearing media, when carrying computer-readable instructionsthat direct functions of the invention, represent embodiments of theinvention.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method for determining an end-to-end measure of quality for aservice provided in a packet-switched network operated by a serviceprovider, comprising: obtaining, by a server of the service provider,network measurement data for network components within thepacket-switched network utilized to provide the service; acquiring, bythe server of the service provider, network estimation data for anaccess network and an access link outside of the packet-switched networkand operated by a different service provider utilized to provide theservice, wherein the network estimation data is directly obtained bynetwork probes sent from the packet-switched network, wherein thenetwork probes comprise time stamped requests used to measure a tendencyof the access network to exhibit jitter and to estimate characteristicsof the access links including at least bandwidth capacity; andcalculating, by the server of the service provider, the end-to-endmeasure of quality for the service from the network measurement data andthe network estimation data, wherein the calculating comprises:conducting reliability estimates for the access network and the accesslink utilizing the network estimation data; and processing the networkmeasurement data and the reliability estimates to derive the end-to-endmeasure of quality.
 2. The method of claim 1, wherein the networkmeasurement data comprises a mean time to failure of a component powersupply.
 3. The method of claim 1, wherein the network probes comprisetest scripts utilized to measure the access network.
 4. The method ofclaim 1, wherein the packet-switched network comprises an internetprotocol network.
 5. The method of claim 1, wherein the packet-switchednetwork comprises a voice over internet protocol network.
 6. The methodof claim 1, wherein the network measurement data comprises networkcomponent failover characteristics.
 7. An apparatus for determining anend-to-end measure of for a service provided in a packet-switchednetwork operated by a service provider, comprising: a server comprisinga processor, and a computer-readable medium in communication with theprocessor, the computer-readable medium having stored thereon aplurality of instructions which, when executed by the processor, causethe processor to perform operations, the operations comprising:obtaining network measurement data for network components within thepacket-switched network utilized to provide the service; acquiring, forthe service provider, network estimation data for an access network andan access link outside of the packet-switched network and operated by adifferent service provider utilized to provide the service, wherein thenetwork estimation data is directly obtained by network probes sent fromthe packet-switched network, wherein the network probes comprise timestamped requests used to measure a tendency of the access network toexhibit jitter and to estimate characteristics of the access linksincluding at least bandwidth capacity; and calculating the end-to-endmeasure of quality for the service from the network measurement data andthe network estimation data, by: conducting reliability estimates forthe access network and the access link utilizing the network estimationdata; and processing the network measurement data and the reliabilityestimates to derive the end-to-end measure of quality.
 8. The apparatusof claim 7, wherein the network measurement data comprises a mean timeto failure of a component power supply.
 9. The apparatus of claim 7,wherein the network probes comprise test scripts utilized to measure theaccess network.
 10. The apparatus of claim 7, wherein thepacket-switched network comprises an internet protocol network.
 11. Theapparatus of claim 7, wherein the packet-switched network comprises avoice over internet protocol network.
 12. The apparatus of claim 7,wherein the network measurement data comprises network componentfailover characteristics.
 13. A non-transitory computer readable mediumhaving stored thereon instructions that, when executed by a processor ofa server of a service provider, cause the processor to performoperations for determining an end-to-end measure of quality for aservice provided in a packet-switched network operated by the serviceprovider, the operations comprising: obtaining network measurement datafor network components within the packet-switched network utilized toprovide the service; acquiring network estimation data for an accessnetwork and an access link outside of the packet-switched network andoperated by a different service provider utilized to provide theservice, wherein the network estimation data is directly obtained bynetwork probes sent from the packet-switched network, wherein thenetwork probes comprise time stamped requests used to measure a tendencyof the access network to exhibit jitter and to estimate characteristicsof the access links including at least bandwidth capacity; andcalculating the end-to-end measure of quality for the service from thenetwork measurement data and the network estimation data, wherein thecalculating comprises: conducting reliability estimates for the accessnetwork and the access link utilizing the network estimation data; andprocessing the network measurement data and the reliability estimates toderive the end-to-end measure of quality.
 14. The non-transitorycomputer readable medium of claim 13, wherein the network measurementdata comprises a mean time to failure of a component power supply. 15.The non-transitory computer readable medium of claim 13, wherein thenetwork probes comprise test scripts utilized to measure the accessnetwork.
 16. The non-transitory computer readable medium of claim 13,wherein the packet-switched network comprises a voice over internetprotocol network.
 17. The non-transitory computer readable medium ofclaim 13, wherein the network measurement data comprises networkcomponent failover characteristics.